The Don’ts of Blow-Out Winterization

Compressed air can be an effective tool for freeing an irrigation system of water, but it can also damage a system if it’s not used correctly. Contractors can prevent system damage by staying within its pressure limits, says Kevin Gordon, senior product development manager, Hunter Industries, San Marcos, Calif.

“When winterizing a system, the most important thing to remember is to never exceed the maximum operating pressure of the product,” he says. “It sounds simple and easy, but it’s a step that’s often overlooked. Air is actually more dangerous than water in a lot of respects because it’s compressible, and on systems with check valves, those check valves will hold the air back, causing some pretty explosive reactions when that check valve finally releases.”

With that in mind, Hunter Industries provides the five “do nots” of blow-out winterization on its Web site at www.hunterindustries.com. They are:

• Do not allow the air pressure to exceed 80 psi for systems with PVC piping and 50 psi for systems with polyethylene piping.
• Do not stand over component parts while the system is pressurized with air.
• Do not leave the air compressor unattended
• Do not blow the system out through a backflow or pump. First blow out the system, then drain the backflow or pump.
• Do not leave the manual drain valves open after the blow-out.